Study: star-nosed mole offers clues to mammalian touch mechanism

Today's freaky mole news comes courtesy of biologists who have
been studying the star-nosed mole, most recognisable for the 11
pairs of feelers on its nose that give a hypersensitive sense of
touch for underground navigation. It turns out that the
peculiar nose may hold clues for new methods of treating human
diseases such as arthritis.

The reason for this comes down to the interconnectedness of the
sensations of touch and pain. The biologists who compiled this
study looked at the nose of this mole because it has the highest
densities of nerve endings of any mammalian skin in the animal
kingdom. Some moles have over 100,000 nerve endings per centimetre
of skin, which gives them such a fine tactile sense it can only
take 120 milliseconds to sort small prey from the surrounding
soil and determine if it's edible.

Kristin Gerhold and Maurizio Pellegrino, from the
University of California, Berkeley, led the study to look at this
dense collection of nerve endings. They found that there was a high
density of a kind of neuron known to be sensitive to a light touch
in the nose skin, along with a lower proportion of neurons that
respond to pain. The result is a nose that, while extraordinarily
sensitive to touching things, may well be poor at detecting
"thermal or chemical" sensations.

This specialisation into a specific kind of touch neuron let the
researchers narrow down which particular molecules are involved in
the chemical process where a sensation is translated into a nerve
signal, as well as which genes create the neuron specialisation.
These same genes were also found in mice and human genomes,
indicating that the same mechanisms for touch may be replicated
across the mammal kingdom.

Gerhold writes: "Our results emphasise the utility of
examining both traditional model organisms and less common species
that may provide important clues to sensory system function.
We exploited the high tactile acuity of the star-nosed
mole to identify a multitude of candidate molecules that may
mediate innocuous and noxious somatosensory stimuli. The function
of these molecules can now be probed in more traditional model
organisms."